Magnetic separator



, 1969 w. PIXLEY MAGNETIC SEPARATOR March 1 1 Sheet of Filed April 14. 1967 March 11, 1969 w. l. PIXLEY 3,432,037

MAGNETIC SEPARATOR l Flled Apnl 4, 1967 Sheet 2 of 3 March 11, 1969 w. l. PIXLEY 3,432,037

MAGNETIC SEPARATOR Flled Aprll 14, 1967 Sheet 3 of FIG.6.

FIG.5.

United States Patent 3 Claims ABSTRACT OF DISCLOSURE The separator has a stationary magnet positioned so that the magnetic flux is concentrated over the path of a mixture to draw the magnetizable material from the mixture and hold it against a portion of a member positioned between the mixture and the magnet. The member is oscillated in opposite directions transverse to the path of travel of the mixture of materials thereby to draw the magnetizable material against it. The fl-ux density at the sides of said path of travel is less than that required to hold the magnetizable material against the nonmagnetizable member, thereby permitting the magnetizable material to drop from the member alternately at opposite sides of the path of travel.

Background of the invention This invention relates to magnetic separators useful for removing magnetizable materials from a mixture of materials comprising both magnetizable and nonmagnetic materials. Such separators of various types have been used for such purposes. Typically, a prior-art separator includes a magnet positioned over a conveyor belt carrying a mixture of material. The separator 'has a moving flexible conveyor belt with its lower reach between the magnet and the material. The magnetizable material is attracted toward the magnet and engages the conveyor belt of the separator. This belt carries the material out of the magnetic field where it drops from the surface of the separator belt. The separator may be positioned to carry away the magnetizable material either in line with the path of travel of the mixture of materials, or transversely. The flexible separator belts, which are usually resilient and nonmetallic, are frequently cut or lacerated by the materials as they engage the belts. This reduces the useful life of such belts. Also, since the separator belts travel in one direction, over the conveyor belt, all of the magnetizable material is discharged from the separator on one side of the conveyor belt, even when the path of travel of the belt is transverse to the path of travel of the material beneath the separator.

Summary 09 the invention Accordingly, objects of the invention include the provision of a high-capacity, self-cleaning, magnetic separator which is not subject to damaging cutting or lacerations and which deposits magnetizable material alternately at both sides of the path of travel of a mixture of magnetizable and nonmagnetic materials.

Brief description of the drawings FIG. 1 is an end view of one embodiment of a magnetic separator of the invention;

FIG. 2 is a section taken along line 2-2 of FIG. 1;

FIG. 3 is a side view of another embodiment of the invention;

FIG. 4 is an end view, partially broken away, taken from the right side of FIG. 3;

FIG. 5 is a fragmentary ideal section taken along line 5-5 of FIG. 3; and v FIG. 6 is a fragmentary ideal section taken along line 6-6 of FIG. 3.

3,432,037 Patented Mar. 11, 1969 Corresponding reference characters indicate corresponding parts throughout the several views of the drawmgs.

Description of the preferred embodiments Referring to FIGS. 1 and 2, a mixture of materials is shown at 1 which comprises both magnetizable materials and nonmagnetic or nonmagnetizable materials. The mixture of materials may comprise slag and magnetizable metal parts which are to be abstracted.. The material is carried by a belt-type conveyor 3 which travels beneath or through the separator.

The separator comprises a magnet 5 which is supported in a fixed position by a pair of I-beams 7 attached at their ends to cross beams 9 which straddle conveyor 3. The cross beams are supported by four upright posts or standards 11, two of which are located at each side of the conveyor. The magnet 5 is preferably positioned immediately above the conveyor so that the magnetic field is concentrated in the area immediately above the conveyor. The magnet may be either a permanent magnet or an electrom-agnet. The standards 11 also support a pair of cross frame members 13 which mount a stationary shaft 15. The axis of shaft 15 is substantially parallel to the path of travel of the material 1 on the conveyor 3 and it is located directly above the conveyor as shown in FIG. 1.

Carried on and pivoted by the shaft 15 is a rocking structure or assembly generally designated 17. This comprises four support members 19 which. are attached at their upper ends to bearings 21 carried by shaft 15 and to an arcuate wear-resistant nonmagnetizable metal plate 23 positioned between the conveyor 3 and the magnet 5. The metal may be stainless steel, manganese steel or the like. Plate 23 is in the shape of the segment of a cylinder having its axis coaxial with the center of shaft 15. This shape, together with the mounting of the assembly 17 on the shaft, provides for a substantially constant spacing between material 1 and some segment of the plate during swinging movement of the plate about the shaft.

There are a plurality of spaced, generally parallel nonmagnetizable ribs 24 fixed by welding to the lower surface of plate 23 and extending generally parallel to the path of travel of the material 1. These ribs restrict lateral sliding movement of magnetizable material on the lower, surface of the plate when the assembly 17 is rocked.

Plate 23 is oscillated between the solidand dotted-line positions shown in FIG. 1 by a motor 25 supported by frame members 13. The motor rotates a crank arm 27 to move a link 29 connected to the crank arm and to one of the support members 19 of the rocking structure. The plate 23 is thus oscillated transversely relative to the path of travel of the material 1 carried by the conveyor 3. The extent of swinging movement is limited so that some portion of the plate is always positioned immediately above material 1 and beneath the magnet 5.

The flux field of the magnet is concentrated beneath the magnet 5 so that as material 1 travels under it, the magnet attracts magnetizable material from the material 1 and lifts these objects and holds them against the lower surface of the plate 23 as long as they are immediately beneath the magnet. The magnetic flux density from magnet 5 is low in the areas transverse of the magnet.

The term nonmagnetizable metal as used herein refers not only to materials which cannot be magnetized but also to materials which have a very low magnetic retentivity of remanence. Thus the portions of the plate 23 spaced laterally from magnet 5 have very little or no magnetic attraction for magnetic pieces from material 1 even after said portions of the plate have just passed through the field of the magnet 5. Therefore the magnetic flux from the magnet is insufficient to hold the magnetizable particles or pieces against the plate 3 after they have moved With the plate laterally to one side or the other of conveyor 3 and magnet 5. In other words the magnetizable particles lose enough of their magnetism to fall off.

Operation is as follows:

Assume that the conveyor 3 is moving the material 1 through or beneath the separator and that the material 1 comprises dry slag or other material having therein magnetizable parts or pieces which are to be abstracted. Motor 25 is turned on and rocks the structure 17 back and forth about the axis of shaft 15, thereby oscillating plate 23 beneath magnet 25 and above the material 1. During this movement some portion of the plate 23 is always moving in one direction or the other beneath the lower face of magnet and above the material 1.

As the material 1 is moved into the flux field of the magnet 5, the magnetizable particles or pieces of the material 1 are magnetized and attracted toward the magnet 5, thereby being pulled upwardly against the lower surface of the plate 23 as shown by the arrows 33 in FIGS. 1 and 2. These metal particles or pieces, due to the relatively high flux density immediately over conveyor 1 and beneath the magnet 5, are held against the lower surface of the plate while it is above the conveyor 3. The particles held against the plate 23 are moved with the plate laterally with respect to the path of travel of the material 1 until the particles are at the side of the path of travel of the material 1 and out of the area of high magnetic flux density. When the particles are at the side of the conveyor 1 and magnet 5, where the flux density is significantly less, the force of gravity pulls the material from the plate. Some of the magnetizable pieces are dumped at each side of the conveyor as shown by the dotted-line arrows 35 in FIG. 1. During movement of rocking assembly 17, the magnetiza ble material cannot be drawn very far back along the surface of plate 23 because of interference by the ribs 24. This prevents any substantial accumulation of the material on plate 23 beneath the magnet. Thus the separator is self cleaning. There is a dwell when the rocking assembly reaches the two opposite dotted-line positions in FIG. 1 and reverses its direction of travel. During these dwells magnetizable material may accumulate to a considerable depth on the sector plate 23. This is ad vantageous since it reduces the gap and the reluctance of the magnetic field over the material 1. This increases the total amount of magnetizable material that can be removed during a pass of a given length of the belt 3 through the separator.

FIGS. 3-6 show another embodiment of the separator used for removing magnetiza ble pieces or particles of material from an inclined conveyor designated 3a. In this embodiment beams 5' are offset vertically so that the lower face of the magnet is substantially parallel to the surface of the conveyor material 1. As in the previous embodiment, the magnet 5 is fixed directly over material 1.

The standards 11 carry the cross members 13. In this embodiment, bearings 41 journal a shaft 43 on frame members 13. The shaft is positioned immediately above conveyor 3a and is generally parallel to the horizontal component of the path of travel of material 1. Shaft 43 comprises part of a rocking assembly generally designated 45 which also comprises a hard, nonmagnetiza- 'ble plate 47 which is supported in an inclined position directly over material 1 and beneath the magnet 5 by a pair of rocker frame assemblies designated 49a and 4912. Plate 47 is generally in the shape of a sector of a cone having an axiscoaxial with the shaft 43. Ribs 48 are secured by welding to the lower face of the plate 47.

The assembly 49a comprises a pair of side arms 51a (FIG. 5 which are joined at their upper ends to a channel 53a and at their lower ends to a rib 55a. The channel 53a is secured to shaft 43 for rotation with it. Similarly, the frame assembly 4% comprises side arms 5112 (FIG. 4) which are joined to a channel 53b and a rib 55b. Ribs 55a, 55b are secured to opposite edges of the conical plate 47. The frame assemblies 49a, 49b are joined by a pair of channel members 57 which are secured to the arms 51a and 51b at their lower ends. The frame assemblies support conical plate 47 in the position wherein its lowermost part is substantially parallel to the path of travel of the material 1 on conveyor 3a.

The frame assemblies and the plate 47 are oscillated or rocked back and forth about the axis of shaft 43 by a motor 59 which drives a crank arm 61 connected to one end of a link 63. The other end of the link is connected to an arm 51b of the frame assembly 4912. Motor 59 is supported by frame members 13.

In operation, the frame assemblies 49a, 49b are rocked back and forth about the axis of shaft 43 by operation of motor 59 to swing the conical plate 47 back and forth transverse to the path of movement of the material 1. The magnetizable pieces in the material 1 are drawn upwardly by the field of the magnet 5, the magnetic flux being concentrated immediately above the material 1. The magnetic material engages and is held against the lower surface of plate 47 by magnet 5 while the material is adjacent magnet 5 on plate 47. As the plate swings back and forth the material is carried laterally out of the main concentration of the magnetic flux of the field from magnet 5 Where the flux density is less than that required to hold the material on the plate 47 At this time the material is at the side of the conveyor 3a and drops from the plate to the side of the conveyor as shown by the dotted arrows 65 in FIG. 4. The ribs 48 on plate 47 prevent the material from sliding around the conic surface of plate 47.

Since the plates 23 and 47 are preferably formed of a hard substance, they are not cut or lacerated by the pieces drawn to them and impinging thereon. The separator of the invention can be used with either horizontal conveyors as shown in FIGS. 1 and 2 or with inclined conveyors as shown in FIGS. 3 and 4. While the sector 23 of FIGS. 1 and 2 is cylindrical and the sector 47 of FIGS. 3-6 is conical, each may be referred to as being barrel-shaped. They provide zones of plate material under the magnet which reciprocate crosswise of the path of the mixture 1 on the supporting belt conveyor.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A magnetic separator for removing magnetizable material from a mixture thereof with a substantially nonmagnetizable material and traveling along .a path which has a substantially straight portion, comprising a supporting framework extending over said straight portion of the path, a shaft, bearings carrying said shaft on said framework above said path, the axis of the shaft being substantially parallel to the horizontal component of said straight portion of the path, a barrel-shaped nonmagnetizable metal sector plate extending across and above said path, the axis of the sector plate being coincident with that of the shaft, a suspension from the shaft for the sector plate, a rotatable driving crank, a linkage connecting the crank with the suspension at a radial distance from the axis of the shaft which is less than the outside radius of the sector plate for substantially angularly oscillating said sector transversely of the path with a minimum radius of said crank, and magnetizing means supported 5 near the sector plate between it and the shaft and located above said straight portion of the path.

2. A separator made according to claim .1, wherein the lower face of the magnet slopes and the sector is conical for use above a path which slopes.

3. A separator made according to claim 1, wherein the lower face of the magnet is level and the sector is cylindrical for use above a path which is level.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 10/ 1920 Great Britain.

TIM R. MILES, Primary Examiner.

U.S. Cl. X.R. 

